This invention relates to a tangential belt drive mechanism for spinning rotors of spinning units of an open-end spinning machine, wherein a tangential belt is pressed, in the zone of each spinning unit, against a rotor shaft with a spring-loaded, movable pressure (contact) roll, which latter can be moved away from the rotor shaft in order to interrupt the drive.
In a conventional type of construction of U.S. Pat. No. 3,868,815 dated Mar. 4, 1975 (DOS[German Unexamined Laid-Open Application]21 41 276), wherein the rotor shafts of the spinning rotors are supported in V-slots formed by pairs of supporting disks, the pressure roll of the respective spinning unit is moved away from the rotor shaft in order to arrest a spinning rotor, while simultaneously a brake is applied to the rotor shaft. The tangential belt relieved of the pressure roll then drags over the rotor shaft arrested by means of the brake. Since the tangential belt in this case contacts the rotor shaft with a substantially lesser tension than in the operation condition, this type of arresting a spinning rotor can be permissible, insofar as this need not be done over a rather long period of time. However, if longer periods of a standstill are to be expected, there is the danger that increased wear occurs in such a case after a longer operating time.
In tangential belt drive mechanisms for spinning spindles, it has been known (German Patent 20 48 959) to lift the tangential belt upon a standstill of the device to such an extent that the connection of the spindle to the tangential belt is entirely interrupted. In this type of structure, in order to interrupt the drive operation, it is not the pressure roll which is relieved in order to interrupt the drive, but rather the tangential belt is moved away from the spindle with the aid of two additional lifting rollers. This type of construction requires, on the one hand, a considerable expenditure and, on the other hand, leads to an increased stress on the belt, since relatively great deflections of the tangential belt are effected for the arresting step, so that the belt can be lifted completely off the spindle.
The invention is based on the problem of fashioning a tangential belt drive mechanism of the type mentioned in the foregoing so that the tangential belt, during the arresting of a spinning rotor, is entirely free of the braked rotor shaft without subjecting the belt to additional stresses by such a disengagement from the rotor shaft. This problem is solved by providing that stationary guide rollers are arranged on the side of the tangential belt facing away from the pressure rollers, the periphery of these guide rollers, conducting the tangential belt, being offset with respect to the neighboring rotor shafts so that a common tangent laid from this peripheral zone of the guide rollers to the peripheral zone guiding the tangential belt on the same side and pertaining to the component following the neighboring rotor shafts passes by (extends past) the neighboring rotor shafts. By means of these stationary guide rollers, a belt path is fixed for the unstressed tangential belt which leads past the rotor shafts. The rotor shafts are driven if the tangential belt is especially brought into engagement with these shafts by means of the associated pressure rollers. It is possible, in this connection, to operate with minor offet positions, especially if the pressure rollers are arranged relatively closely adjacent the associated rotor shafts, so that the deflections between the operating condition and the braking condition are practically not varied appreciably for the tangential belt. This arrangement has the advantage that only a small structural expenditure is required, especially since no additional parts are required which have to be adjusted during the braking step.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.